The field to which our invention relates is known as Electrical Discharge Machining, hereinafter referred to as "EDM" in which material is removed from an electrically conductive workpiece by the action of electrical gap discharges between one or more electrodes and the workpiece. The servo feed system is employed to provide relative movement thus to maintain a relatively constant and optimum gap spacing between the electrode and workpiece as material is progressively removed from the workpiece.
A dielectric fluid is circulated and recirculated, generally under pressure to the gap throughout the machining operation. For most reliable and dependable results, a power supply of the independent pulse generator type is utilized to provide machining power pulses of precisely controllable frequency and on/off times. One type of multivibrator, particularly suitable for EDM operation, is described and disclosed in Bell, U.S. Pat. No. 3,809,848, issued on May 7, 1974, for "Digitally Controlled Power Supply for Electrical Discharge Machining Apparatus".